Astrology Decans: The Three Faces of Every Zodiac Sign

Astrology decans divide each 30-degree zodiac sign into three 10-degree segments, giving 36 decans across the full circle, each with its own sub-ruler. The system began as 36 Egyptian star groups used to tell time at night and was absorbed into Hellenistic astrology as a way to read a sign in finer detail. Knowing your decan tells you which of the three faces of your sun sign you were actually born under.

What are astrology decans and how do they divide the zodiac?

Astrology decans are the three 10-degree segments inside every 30-degree zodiac sign, which produces 36 decans across the 360-degree circle. Degrees 0 through 9 form the first decan, degrees 10 through 19 the second, and degrees 20 through 29 the third. Every point in the zodiac belongs to one decan and only one, so a planet at 14 degrees Virgo sits in the second decan of Virgo and nowhere else. The decan meaning in astrology comes from the sub-ruler attached to each segment. A sign already has a ruling planet, and the decan layers a second planetary or sign influence on top of it, which is why practitioners describe the three decans as the three faces of a sign rather than three moods of it. The word face is not decorative. Medieval Latin texts call the decan a facies and the Arabic sources call it a wajh, both meaning face. In that older material the face is a minor dignity: a planet in its own face has a small measure of strength, enough to steady it but not enough to make it powerful.

The arithmetic is what makes zodiac decans useful. A sun sign covers roughly thirty days, and thirty days is a wide net for one description. Decans cut that net into three ten-day panels, so a description can be built for a stretch of birthdays rather than a whole month. That is the practical proposition of decanate astrology: a sun sign reading that holds for one third of the people it used to cover holds tighter. The 36 decans also interlock with the rest of the sign framework rather than competing with it. Each sign keeps its element and its modality, covered in Fire, Earth, Air & Water: The Four Elements in Astrology and Cardinal, Fixed & Mutable Signs: The Three Modalities Explained, and the decan sits underneath both as a third layer of detail. Nothing about the decan overrides the sign. A third decan Taurus is still fixed, still earth, still Venus-ruled at the sign level. The decan tells you which version of that Taurus showed up.

How many decans are there in the zodiac in total?

There are 36 decans in the zodiac in total: twelve signs at three decans each. The number is not arbitrary. Thirty-six segments of 10 degrees fill 360 degrees exactly, and 36 periods of ten days fill 360 days, which is why the division worked as a calendar before it worked as a character system.

Why are decans called faces in older astrology books?

Decans are called faces in older astrology books because the medieval Latin term for the 10-degree division was facies, translated from the Arabic wajh. In that tradition the face is the weakest of the essential dignities, worth a single point, so a planet in its own face is described as barely holding its footing rather than commanding the ground.

Where did the decans come from in Egyptian and Hellenistic astrology?

The decans began in ancient Egypt as 36 star groups used to tell time at night, long before they had anything to do with zodiac signs. Each decan star rose just before dawn for roughly ten days before the next one took over, and the succession of 36 such risings tracked the Egyptian civil year of 360 days plus five added days at the end. Egyptian astronomers painted these star groups in tables on coffin lids and later across temple ceilings, arranged in diagonal grids that let a reader work out the hour of the night from which decan was rising. Sirius, known to the Egyptians as Sothis, was the most important star in the scheme, since its heliacal rising marked the turn of the year. The standard account of why a night has twelve hours points straight at this system: roughly twelve decans rise across a single night, and each one marked an hour. The decans were timekeepers and gods before they were personality descriptions.

The transfer into astrology happened in Hellenistic Egypt, where Greek astronomical zodiac signs met the older Egyptian star calendar. The zodiac had 360 degrees. The Egyptians had 36 decans. Someone mapped one onto the other, giving each sign three decans of ten degrees, and the decans stopped being stars and became segments of the ecliptic. That change matters more than it sounds, because the segments no longer track the stars they were named for. Once decans were measured from the equinox rather than from the actual rising of a star group, precession pulled the two apart, and the drift has accumulated for two thousand years. Hellenistic and later authors treated the decans unevenly. Some worked them hard as a source of imagery and talismanic power. Ptolemy gave them little weight, preferring the finer unequal divisions called terms or bounds. The medieval Arabic and Latin tradition brought them back as the faces, and the grimoire tradition kept the decan images alive when the technical astrologers had largely moved on.

Were Egyptian decans stars or zodiac divisions?

Egyptian decans were stars first. They were 36 identifiable star groups whose successive predawn risings, about ten days apart, told Egyptian observers the hour of the night and the position of the year. Only in the Hellenistic period were the decans redefined as fixed 10-degree divisions of the zodiac, at which point they stopped following the stars that named them.

What are the decan images in the magical tradition?

The decan images are the symbolic figures assigned to each of the 36 decans in the talismanic tradition. The Picatrix and Agrippa's Three Books of Occult Philosophy both record a picture for every decan, described as a person, animal, or scene, intended to be engraved on a talisman while the corresponding degrees were rising.

How do you find which decan you were born in?

You find your decan by reading the exact degree of your sun in a birth chart and matching it to one of three bands: 0 to 9 degrees is the first decan, 10 to 19 degrees is the second, and 20 to 29 degrees is the third. A chart that reports the sun at 24 degrees 12 minutes of Aquarius puts you in the third decan of Aquarius. That is the whole procedure, and it works identically for the moon, the ascendant, or any planet. Without a chart, you can approximate from your birthday by counting from the day the sun entered your sign. Roughly the first ten days of the sign are the first decan, the middle ten the second, and the final ten the third. For Aries that lands near March 21 to 30, March 31 to April 9, and April 10 to 19. Those dates move by a day in either direction depending on the year, so a birthday sitting on a boundary needs a real calculation rather than a table. If you are not sure which sign you fall under to begin with, What Zodiac Sign Am I? Find Your Sun Sign by Birthday sorts that out first.

Birth time matters at the edges and nowhere else. The sun moves close to one degree per day, so it crosses a decan boundary at a particular hour on a particular date. A person born at 4 a.m. on the day the sun reaches 10 degrees of Gemini may still be in the first decan; a person born that evening is in the second. Away from the boundaries, the sun sits comfortably mid-decan and no birth time is required. Charts also let you read decans for more than the sun, which is where the technique earns its keep. A Venus at 27 degrees Libra and a Venus at 2 degrees Libra behave differently in this system even though both are Venus in Libra. How to Read Your Birth Chart: Complete Beginner's Guide covers pulling those degrees in the first place, and Rising Sign (Ascendant): Your Public Persona Explained covers why the ascendant degree is worth the extra precision.

Do I need my birth time to know my decan?

You need your birth time only if you were born within about a day of a decan boundary. The sun advances roughly one degree per day, so it crosses from 9 degrees to 10 degrees at a specific hour. Away from those crossover dates, the sun sits well inside a decan and the date alone settles the question.

What decan is 29 degrees of a sign?

Twenty-nine degrees of any sign is the third decan, the last of the three, and it sits at the very end of that decan. Twenty-nine degrees also carries a separate reputation in astrology as the anaretic or critical degree, but that is a distinct idea layered on top of the decan rather than part of the decan system.

What are the two decan ruler systems and how do they differ?

Two decan ruler systems dominate practice, and they assign different rulers to the same 10 degrees. The Chaldean system runs the seven traditional planets in their classical speed order, Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, continuously through all 36 decans, beginning with Mars at 0 degrees Aries. It ignores sign boundaries entirely: the sequence just keeps cycling, so the ruler of a decan often has no obvious relationship to the sign it sits in. The triplicity system, sometimes called the modern or sign-based method, assigns each decan to one of the three signs sharing that element, taken in zodiacal order. The first decan of a sign goes to the sign itself, the second to the next sign of the same element, the third to the last. Cancer's decans become Cancer, Scorpio, and Pisces under this method. The two schemes almost never agree. Chaldean gives the first decan of Cancer to Venus; triplicity gives it to Cancer and therefore to the moon. Most disagreements about decan meaning in astrology trace back to two writers using different systems without saying so.

The Chaldean sequence has a quirk worth knowing, because it reveals how the system was built. Thirty-six does not divide by seven, so the planetary cycle does not close cleanly across the zodiac. Running the order from Mars at Aries, the thirty-sixth decan, the last face of Pisces, also lands on Mars, and then the sequence is reset by hand so that Aries begins with Mars again. Mars therefore appears twice in a row across the Pisces to Aries boundary, at the exact seam of the zodiac. Traditional astrologers read that doubled Mars as the hinge of the year, not an error. The triplicity method has a different pedigree. It matches how Indian astrology assigns the drekkana, and it became the default in twentieth-century sun-sign columns because it is easy to explain: your first decan is you doubled, your second borrows from the next sign of your element, your third from the last. Traditional and magical practice leans Chaldean. Popular decanate astrology leans triplicity.

What is the Chaldean order of planets used for decans?

The Chaldean order used for decan rulers is Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, arranged by apparent speed from slowest to fastest. Decan assignment starts at Mars for 0 to 9 degrees of Aries and cycles through that list continuously, one planet per decan, across all 36 decans without restarting at sign boundaries.

How does the triplicity decan system work?

The triplicity decan system gives each decan to a sign of the same element, in zodiacal order. Aries decans go to Aries, Leo, and Sagittarius; Libra decans go to Libra, Aquarius, and Gemini. The first decan always belongs to the sign itself, which is why this method reads the first decan as the most concentrated version of the sign.

What are all 36 decans and their Chaldean sub-rulers?

The 36 decans and their Chaldean sub-rulers run as one unbroken planetary cycle from Aries through Pisces. Aries takes Mars, Sun, Venus. Taurus takes Mercury, Moon, Saturn. Gemini takes Jupiter, Mars, Sun. Cancer takes Venus, Mercury, Moon. Leo takes Saturn, Jupiter, Mars. Virgo takes Sun, Venus, Mercury. Libra takes Moon, Saturn, Jupiter. Scorpio takes Mars, Sun, Venus. Sagittarius takes Mercury, Moon, Saturn. Capricorn takes Jupiter, Mars, Sun. Aquarius takes Venus, Mercury, Moon. Pisces takes Saturn, Jupiter, Mars. Read down that list and the seven-planet order repeats cleanly, which is what produces the doubled Mars at the Pisces-Aries seam. Every planet ends up ruling five or six decans scattered across all four elements, so Saturn governs the third face of Taurus, the first of Leo, the second of Libra, the third of Sagittarius, and the first of Pisces. In this system a decan ruler does not have to be friendly to its sign, and the interesting readings come from the mismatches.

The mismatches are the point. Saturn ruling the first face of Leo is the classic example, because Saturn and the sun are traditionally at odds and Leo is the sun's own sign. Practitioners read that decan as a Leo with a cold streak and a long fuse, ambitious in a structural way rather than a theatrical one, more likely to build an institution than to perform. Venus on the third face of Scorpio is another: Scorpio's Mars-driven intensity handed to the planet of attraction, which reads as magnetism with a sting in it. Compare that to Mars on the first face of Scorpio, where sign ruler and decan ruler agree and the result is Scorpio at full undiluted strength. Traditional astrologers also use these assignments as a minor dignity rather than a personality label. A planet in its own face gains a single point of essential dignity, the smallest amount available, so it is not dignified so much as not homeless.

Why does Mars rule two decans in a row?

Mars rules two decans in a row because 36 does not divide evenly by seven. Running the Chaldean order from Mars at 0 degrees Aries, the final face of Pisces also falls to Mars, and the cycle is then reset so Aries starts on Mars again. The result is Mars on both sides of the zodiac's starting line.

Which planet rules the first decan of each sign in the Chaldean system?

In the Chaldean system the first decan rulers run Mars for Aries, Mercury for Taurus, Jupiter for Gemini, Venus for Cancer, Saturn for Leo, Sun for Virgo, Moon for Libra, Mars for Scorpio, Mercury for Sagittarius, Jupiter for Capricorn, Venus for Aquarius, and Saturn for Pisces.

What does the first decan of a sign mean compared to the second and third?

The first decan of a sign is read as that sign at its most concentrated, at least in the triplicity system, because the first decan belongs to the sign itself. A first decan Capricorn is Capricorn without a second flavor: structural, patient, unhurried about proving anything. The second decan borrows from the next sign of the same element, which redirects the sign's drive toward a different end. Second decan Capricorn takes on Taurus, so the ambition softens toward comfort, security, and things that can be touched. The third decan takes the last sign of the element, which usually adds analysis or refinement. Third decan Capricorn takes Virgo, and the reading becomes exacting, detail-driven, more editor than executive. The same three-step shape applies across the zodiac: first decan is pure sign, second decan is the sign pulled sideways, third decan is the sign specialized. Under the Chaldean system the logic is different, because the sub-ruler is a planet with no guaranteed relationship to the sign, and a first decan can be sharply at odds with the sign it opens.

Practitioners often describe the three decans as a developmental arc: raw expression, then the sign in relationship with something outside itself, then the sign refined toward its most specific use. That framing is a reading habit rather than a rule anyone can point to in a Hellenistic text, and it is worth holding loosely. What it does well is explain the persistent complaint that a sun sign description feels only half right. Two Sagittarians can genuinely diverge, since the doubled first decan Sagittarius is the one who books the ticket while the third decan Sagittarius carries Leo and wants an audience for the story afterward. The value of decanate astrology is not that it makes a sun sign reading correct. It is that it gives you a defensible reason why two people with the same sign read differently, without resorting to the vague language of cusps.

What does the second decan add to a sign?

The second decan adds the next sign of the same element, which pulls the original sign's motivation toward a different target. Second decan Aries picks up Leo and becomes more performance-driven than the first; second decan Pisces picks up Cancer and becomes more protective and family-anchored than the first.

Does the third decan mean you are less like your sign?

The third decan does not make you less like your sign. It specializes the sign toward the qualities of the final sign in its element. A third decan Gemini carries Aquarius and reads as more ideological and less scattered than a first decan Gemini, but the Gemini foundation of curiosity and language is unchanged.

How do decans refine a sun sign reading in practice?

Decans refine a sun sign reading by cutting a month-wide description into three ten-day descriptions, which raises the resolution without requiring a full chart. A generic Virgo profile has to cover people born on August 24 and September 21, which is a lot of ground for one paragraph. Splitting Virgo into its three decans gives you a sun-ruled first face, a Venus-ruled second face, and a Mercury-ruled third face under the Chaldean scheme, and each of those reads distinctly: the first proud of its competence, the second drawn to beauty and to making things pleasant, the third the most classically Mercurial and analytical of the three. That is a real gain in specificity for the cost of knowing one number. Decans also refine timing. Transits are exact by degree, not by sign, so a slow planet crossing 5 degrees of a sign is squaring, opposing, or conjoining first decan placements and leaving the rest of the sign untouched for weeks. Practitioners who track their own transits notice the decan long before they notice the personality description.

The honest limit is that decan work sharpens a sun sign reading without fixing it. A sun sign is one factor in a chart, and dividing that one factor into thirds does not add the moon, the ascendant, the houses, or the aspects. A third decan Aries with a Cancer moon and a Capricorn rising is not going to recognize herself in any Aries decan description, and that is a chart problem rather than a decan problem. Where decan work pays off best is as a first refinement for someone who already reads charts: check which face a stellium is emphasizing, or whether a planet sits in its own face when weighing dignity. The other reliable use is comparison. When two people share a sun sign and read nothing alike, their decans often supply a concrete difference to point at, especially when the sub-rulers are as unlike as Saturn and Mars.

Do decans matter for transits and timing?

Decans matter considerably for timing, because transits are exact by degree. A slow-moving planet spends weeks inside a single decan, so it aspects first decan placements well before it reaches third decan placements in the same sign. Knowing your decan tells you which third of a long transit is actually yours.

Should beginners learn decans early or later?

Beginners are better served learning the sun, moon, ascendant, elements, and modalities before taking on decans. Decans are a refinement layer, and refining a reading that has no foundation under it produces false precision. Once the basic chart is legible, decans are one of the cheapest additions available, since they require no new calculation.

How are decans used in tarot and talismanic magic?

Decans are the backbone of the Golden Dawn's tarot system, where the 36 numbered minor arcana cards from Two through Ten map onto the 36 decans in zodiacal order. The suit follows the element, so the fire signs take Wands, the earth signs take Pentacles or Disks, the air signs take Swords, and the water signs take Cups. The Two of Wands corresponds to the first decan of Aries, ruled by Mars, and the card's Thoth title Dominion follows directly from Mars in the sign of its own rulership. The Ten of Swords corresponds to the third decan of Gemini under the sun and carries the title Ruin. Every pip card in that system is a planet-in-decan formula rather than a free-standing image, which is why Golden Dawn-derived readings feel more astrological than intuitive. Talismanic magic uses the same 36 divisions differently. The Picatrix and Agrippa's Three Books of Occult Philosophy both preserve an image for each decan, and the practice involves electing a moment when the relevant decan is rising and engraving that figure.

The tarot mapping is worth understanding even if you never cast a talisman, because it explains a large amount of standard card meaning that otherwise looks arbitrary. Cards that seem unaccountably grim or unaccountably fortunate usually inherit that tone from the planet-decan pairing behind them, and Golden Dawn-lineage decks encode the assignment on the card itself. The magical tradition took the decans more seriously than the technical astrologers did for several centuries. While Ptolemy and his successors preferred the terms as a dignity system, the grimoire and talisman writers kept all 36 decan images circulating, complete with figures holding tools, riding animals, or standing in specific postures. The overlap with tarot is design rather than coincidence: the Golden Dawn drew from the same body of Hermetic and medieval material, and built a system where a card, a decan, a planet, and a talismanic image all point at the same 10 degrees of sky.

Which tarot cards correspond to the decans?

The 36 numbered minor arcana cards from Two through Ten in all four suits correspond to the 36 decans, one card per decan, in zodiacal order. Aces, court cards, and the major arcana are assigned separately in the Golden Dawn system and do not take decan attributions.

What is a decan talisman?

A decan talisman is an object engraved with the traditional image of one of the 36 decans and made at a moment elected so that decan is rising. The images come from sources such as the Picatrix and Agrippa's Three Books of Occult Philosophy, and the practice treats each decan as a distinct power with a specific sphere of action.

What are the real criticisms and weak points of the decan system?

The strongest criticism of the decan system is that its two rulership schemes contradict each other and most popular writing hides which one it is using. A reader who looks up first decan Leo will be told it is Saturn-flavored and reserved on one site and Leo-doubled and flamboyant on another, with no indication that these come from different methods. That is two opposite portraits of the same birthday, and it makes decan content hard to trust unless the method is stated. A second real problem is drift. The Egyptian decans were star groups, and the Western decan is now a fixed slice measured from the equinox, so the segments no longer correspond to the stars that named them. Anyone claiming that a decan talisman draws on a specific ancient star is asserting a link precession has already broken. A third weak point is commercial: decans are frequently marketed as the hidden reason your horoscope never fit, which oversells a modest refinement layer as a revelation.

There is also a fair internal critique from traditional astrologers, which is that the face was always the weakest dignity in the medieval scheme, worth a single point against a domicile's five. Building an elaborate personality system on the least weighty dignity in the tradition inverts the original priorities. Practitioners who work with faces tend to use them the way the sources did, as a tiebreaker when a planet has no other dignity at all. Against all of that, the timing argument holds up regardless of which scheme you prefer. Transits are exact by degree, and knowing whether your sun sits at 3 or 26 degrees genuinely tells you when a slow transit reaches you. That part is arithmetic. The character interpretation is where the disagreement lives. The reasonable position is the one careful practitioners take: use decans as a resolution increase, name your rulership system, and do not claim more precision than a 10-degree division can carry.

Why do different websites give different decan rulers?

Different websites give different decan rulers because they are using different systems without labeling them. Chaldean sources assign planets in a continuous seven-planet cycle; triplicity sources assign signs of the same element in order. Both are legitimate within their own tradition, and the confusion is entirely a citation problem rather than a dispute about the underlying divisions.

Is there any evidence that decans predict personality?

There is no scientific evidence that decans predict personality, and decan practitioners generally do not claim that framing. The system is presented within astrology as a symbolic language for describing differences within a sign. Treating decan descriptions as measurable psychological findings misrepresents both the tradition and the research record.

How do decans differ from terms, dwads, and other zodiac subdivisions?

Decans differ from the other zodiac subdivisions in size, in whether the segments are equal, and in what they are used for. Terms, also called bounds, divide each sign into five unequal segments ruled by the five non-luminary planets, with sizes varying from sign to sign according to tables preserved from Egyptian and Ptolemaic sources. Terms outrank faces in the dignity hierarchy, counting two points against the face's one. Dwads, short for dwadashamsa, divide each sign into twelve parts of 2 degrees 30 minutes, running through all twelve signs starting from the sign itself, and produce a far finer grain than decans at the cost of demanding an accurate birth time. The Vedic drekkana is the same 10-degree cut as the Western decan, but Indian astrology builds it into a divisional chart, the D-3, read chiefly for siblings, courage, and self-generated effort. Decans sit in the middle: coarse enough that a birthday usually settles them, fine enough to split a sign into three.

The practical reason to keep these straight is that they answer different questions. Terms are a dignity tool, used when weighing whether a planet can act effectively. Decans are a descriptive and timing tool, used to characterize a stretch of a sign and to see which third of it a transit is currently crossing. Dwads are a precision tool for chart readers who already have an exact birth time. Divisional charts in the Indian system are their own discipline, with a full set of charts beyond the D-3 and their own rules of interpretation. Mixing them produces incoherent readings, since a planet can be in its own face, in another planet's term, and in a third sign's dwad simultaneously without any contradiction. Each division answers a separate question about the same degree. Decans stay the most widely used of the four in Western practice, largely because they are the only subdivision you can apply to a sun sign without opening a chart.

What is the difference between decans and terms in astrology?

Decans divide a sign into three equal 10-degree segments ruled by planets in a repeating cycle. Terms, or bounds, divide a sign into five unequal segments ruled by the five non-luminary planets according to preserved tables. Terms carry more weight as an essential dignity than faces do, counting for two points against one.

Are decans used in Vedic astrology?

Vedic astrology uses the same 10-degree division under the name drekkana and builds it into the D-3 divisional chart, read chiefly for siblings, courage, and personal effort. The drekkana assigns each third to a sign of the same element in order, matching the Western triplicity method, though it is calculated in the sidereal zodiac.

Frequently Asked Questions

What are the decans in astrology in one sentence?

The decans in astrology are the three 10-degree segments that make up each 30-degree zodiac sign, producing 36 decans around the full circle, each carrying a sub-ruler that colors the sign it sits inside. A Scorpio born on October 25 and a Scorpio born on November 18 share a sign but not a decan, and practitioners read those two charts differently because of it.

How do I find out which decan I was born in?

To find your decan, get the exact degree of your sun from a birth chart calculator: 0 to 9 degrees of a sign is the first decan, 10 to 19 degrees is the second, and 20 to 29 degrees is the third. Without a chart, count from the day the sun entered your sign, taking the first ten days as the first decan and so on. Anyone born within a day of a boundary needs a birth time, because the sun crosses decan lines at a specific hour, not at midnight.

What is the difference between a decan and a cusp?

A decan is a defined 10-degree segment inside one sign, while a cusp is the informal name for the boundary between two adjacent signs. Every degree of the zodiac belongs to exactly one of the 36 decans, and a birth chart places the sun in one sign or the other even at 29 degrees. A cusp is not a third blended sign. Decan work is precise where cusp talk is usually vague.

Which decan ruler system is correct, Chaldean or triplicity?

Neither decan ruler system is universally correct. Both are in active use and they disagree. The Chaldean system runs the seven traditional planets in the order Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon through all 36 decans starting from Mars at 0 degrees Aries, and it stands behind medieval faces and Golden Dawn tarot attributions. The triplicity system assigns each decan to a sign of the same element in order, and it dominates modern sun-sign writing. Pick one, say which one you are using, and stay consistent.

Does the first decan of a sign mean you are a stronger version of that sign?

In the triplicity system, yes, the first decan of a sign is read as the purest expression of that sign, because the decan is ruled by the sign itself. A first decan Leo is Leo doubled, with no second sign redirecting the energy. The Chaldean system disagrees, giving the first decan of Leo to Saturn, which reads as a far more guarded and self-disciplined Leo. The two systems produce opposite portraits of the same birthday, which is why serious decan work names its method up front.

Are decans the same as the Vedic drekkana?

Decans and the Vedic drekkana are the same 10-degree division applied in two different traditions. Indian astrology calls the third-part the drekkana and builds it into a divisional chart known as the D-3, read chiefly for siblings, courage, and self-generated effort. The largest practical difference is zodiac: Indian astrology works sidereally while most Western decan work is tropical, so a birth degree can land in different decans depending on which zodiac is used.

Do decans change your horoscope predictions?

Decans do not change what transiting planets are doing, but they change when a transit becomes exact for you. A planet crossing 3 degrees of Capricorn touches first decan Capricorn charts and leaves the third decan alone for another two to three weeks. That timing detail is the strongest practical argument for decan work, and the one part of the system that does not depend on which rulership scheme you prefer.